Dynamic Storage

Dynamic storage offers much greater control over your hard disk space. It removes many of the constraints you'll encounter in the basic storage world. With dynamic storage, for example, you can now wipe away the drive letter restrictions of basic disk partitions.

And get this: you can also add space to logical drives without wiping out data and having to start from scratch. If you don't plan on using the disk on another machine, dynamic storage is the preferred method of data storage.

Dynamic storage first appeared on Windows 2000 systems. It divides the usable space on a hard disk not into partitions but rather into volumes. On an XP machine, a volume can be one of two varieties: simple or spanned.

Simple. A simple volume is a slice of storage space from a single dynamic hard drive. The cool part is that the space can come from either contiguous or noncontiguous space from that drive. These volume types are most analogous to a primary partition on a basic disk.

Spanned. A spanned volume contains slices of disk space located acrossspanningmultiple (2 to 32) dynamic hard drives. For example, you can configure a 10GB space from one drive, another 5GB from another drive, and 5GB more from a third drive for a total volume size of 20GB. All the space would be addressed by a single name, usually a drive letter such as D:\, as shown in Figure 4-9.

Figure 4-9. Spanned volumes combine multiple areas into a single drive letter.

Spanned volumes are created to take advantage of unused space across multiple drives; they do not enhance performance. Data is still written sequentially, accessing only one physical disk per I/O request.

So what's the big difference when using one of these dynamic volumes? To many users, nothing. A dynamic volume looks and acts much the way that a partition does; you see a C:\ drive, D:\ drive, and so on, and you can store data in folders on each drive. But what's going on under the hood is significantly different.

One difference is that dynamic disks do notand indeed cannotcontain partitions. This removes almost all restrictions encountered when using partition-based basic disk storage.

It's especially significant if you start to run out of space on the D:\ drive, or any other drive, for that matter. If you're working with a dynamic disk, you can resize the drive with unused space from the disk.

An Exception: Simple Volumes That Have Been Upgraded from a Partition

When you upgrade a basic disk, any existing partitions will be converted into simple volumes, and the size of the volume will be the same as the partition. Unfortunately, these simple volumes cannot be resized like their simple volume brethren that were created from scratch on a dynamic disk.

When you first install Windows XP, the disk is a basic disk. Before we can take advantage of this new storage technology, we must first upgrade our basic disks into dynamic disks. The next chunk outlines this process.